Energy response patterns to light spectrum at sex differentiation stages of Drynaria roosii gametophytes

Abstract

The environmental light changing, such as light spectrum (LS), influences the balance of energy metabolism and sex allocation based on plant species. However, the molecular mechanism underlying systems energy responses (SERs) linked to sex differentiation of Drynaria roosii gametophytes in response to LS remains the enigma. Here, we used Red-LED-Light (RLL), Blue-LED-Light (BLL) and Fluorescent-Light (FL) regimes to treat D. roosii gametophytes to achieve the knowledge of global expression database. Compared with FL, transcriptional changes showed that RLL reduced mRNA levels of photosynthetic genes and improved mRNA levels of respiratory genes. Obviously, RLL decreased PSII/PSI activities with lower Y(II), Fv/Fm, Y(I) and ETR(I) values, and promoted mitochondria activity with higher respiratory rate. Combined with severer ROS stress, we suggested that RLL caused the energy deficit to gametophytes. However, the impacts of BLL were contrary to RLL. Exactly, 63.75 % of males was induced under RLL vs 12.70 % under FL, whilst 64.50 % of females under BLL vs 48.08 % under FL. Moreover, we applied the WGCNA to cluster LS-induced DEGs into eleven modules, and DEGs in five significant sample-specific modules mainly fell in energy metabolism categorization through KEGG pathway analysis. Networks proved the complicated ‘cross-talk’ between SER- and TF-associated genes, and revealed hub genes in response to LS. Based on previous experimental evidence, we supposed a link between LS-induced energy metabolism responses and sex differentiation in D. roosii gametophytes, showing that RLL contributed to male-biased sex ratios for less energy production than BLL and FL, while BLL contributed to a female-biased trend. Our work firstly shed light on SERs to LS in D. roosii gametophytes, and provided new insights for understanding the sex differentiation in ferns.